My boss wants me removed and replaced by another he favours, hence he condemns all I do to the manager, what can I do?

Please help me with the question above as it is a serious situation where good jobs are very difficult to get

Yes, I’m sorry to hear this, I can understand that this would be a serious situation.

If you believe your boss is going to have you replaced with his “favoured” person then you have nothing to lose, and no alternative really, but to discuss it with the manager.

The outcome may not be good, he may not take your side, so be prepared for this to force the situation, but there is nothing else you can realistically do.

If the manager does support you, I wouldn’t imagine your boss will be well pleased. But you never know, he may take your side. May be worth mentioning to him in that case, that you are concerned for your position. And ask for his continued support.

I should start looking around for a new position as soon as you can, and at least be aware of what is available
The very best of luck, however it turns out.